Electrical discharge device and anode therefor



F. E. DIETZ May 27, 1941.

- IN C a 35 BY 2% v ATTORNEY Patented May 27, 1941 UNITED STATES PATENT OFFlCE ELECTRICAL DISCHARGE DEVICE AND AN ODE THEREFOR Fred E. Dietz, Cleveland, Ohio, assignor to Argus Manufacturing Corporation, a corporation of Ohio My invention relates to electrical discharge devices and more particularly to an improved anode or target for such devices.

In electrical discharge devices and particular- 1y those of the rectifier type, it has heretofore been the practice to utilize a carbonaceous material, such as carbon or graphite, or a metal, such as tungsten, platinum or nickel as the anode or target. In rectifying current at high voltage, however, such tubes have not proven satisfactory because when carbon or graphite is utilized as the anode, the high concentration of the energy of the ionic impact at the immediate point of impact causes a local disintegration of the carbon which impairs the efficiency or kills the tube. When metal is utilized as the anode, the bombardment by the ions raises the temperature of the metal to a point at which the anode approaches or assumes a red hot state. Such overheating of the anode is objectionable as it adversely affects the operating characteristics and life of the tube.

It is the aim of the present invention to provide an improved anode for discharge tubes, and particularly those of the gas-filled rectifying type, in which the anode is constructed in such a manner that it will not be heated to an objectionably high temperature nor will it disintegrate in service even when high voltages are being rectified.

It is therefore an object of my invention to provide an improved anode or target for electrical discharge devices.

Another object of my invention is to provide an improved anode or target for gas filled rectifier tubes which is capable of resisting ionic bombardment without becoming objectionably hot or disintegrating even when high voltages are being rectified.

A further object of my invention is to provide an improved electrical discharge device having a conductive outlet rod and an anode or target supported thereby which anode is capable of resisting the ionic bombardment without becoming objectionably hot or disintegrating.

My invention will be better understood by reference to the accompanying drawing in which:

Fig. 1 is a longitudinal sectional view of a rectitying tube, showing my improved anode in elevation;

Fig. 2 is a lower plan view of my improved electrode as viewed from a horizontal plane through the lines 22 of Fig. 1;

Fig. 3 is a cross sectional view on the line 3-3 of Fig. 2; and

Fig. 4 is a view similar toFig. 3 but showing a modified construction.

While my improved anode may be utilized in electrical discharge devices of various types, and I do not desire to be limited thereto, it is par.- ticularly adapted for use in gas-filled tubes for rectifying current at high voltages, such as illustrated in the accompanying drawing in which the numeral l indicates a vitreous tube or envelope having a reentrant portion carrying a stem 2 on which is supported a filamentary cathode 3, the two ends of which are connected to lead in wires 4 and 5. As is usual in rectifiers of this type, the tube is filled with an ionizable gas, such as argon, which may be present in the tube in pressures ranging from a few microns to several millimeters.

My improved anode which constitutes one of the essential features of the present invention is indicated generally by the numeral 5 and may be supported in the tube in any desired manner. For instance, the anode may be supported by an outlet rod or wire I which if desired may be sealed to the tube or envelope in a manner similar to lead in wires 4 and 5, or as illustrated in the drawing, it may pass through and be welded or otherwise secured to a metal disk 8 secured to the vitreous or glass envelope i. As illustrated the metal rod 1 may be anchored to the anode 6 by means of a metal disk 9 welded or otherwise secured to its inner end, but such anchoring I disintegrate or assume an objectionably high temperature in service. For this purpose the body of the anode is formed of a carbonaceous ma-. terial, such as carbon or graphite, and the portion which is subject to ionic bombardment is formed of metal. Any metal may be utilized which is electrically conductive and which has a sufliciently high temperature to withstand the operating temperature of the tube. For instance, I have found that any metal or metal alloy having a higher melting point than copper may be employed, such as nickel, iron, steel, nichrome, tungsten, molybdenum, platinum, tantalum or the like, and when the term metal is utilized in the specification and claims, it is to be understood that this term not only includes elementary metals but also alloys having the desired characteristics.

In the construction of my improved electrode, it is essential that at least a portion of the carbonaceous material be interposed between the may be threaded to receive a threaded metalpl g.

It will be particularly noted that a portion of x the carbonaceous material isinterposed between the metal portion of the anode and the outlet conductor 1 and that the metal portion [0 of the anode is arranged oppositethe cathode 3 material constituting one end portion of said anode and having an opening therein for a con ductor and the metal forming at least a substantial part of the opposite end portion of said anode with its inner surface in contact with the carbonaceous material but spaced from said opening and its outer surface constituting a portion of the surface of said anode.

3. An anode for gas filled rectifier tubes, said anode being solid throughout with the exception of an opening to receive an outlet conductor,

said anode being composed partially of a carbonaceous material and partially of an electricalwhere it is in position to receive ionic bombardment from the cathode 3. Various other forms coming within the purview of my invention may be provided. For instance, the carbon or body portion of the anode may be partially capped with a suitable conductive metal, or a suitable conductive metal Ilia may be sprayed or plated upon that portion of the carbon opposite outlet rod 1 as illustrated in Fig. 4.

The advantages of my improved anode or target when utilized in gas filled rectifying tubes for rectifying current at high voltages has been amply demonstrated in service and the metal In when subjected to high ionic bombardment at such voltages will not become objectionably hot and the carbonaceous material which is not subjected directly to the ionic impacts will not disintegrate. An improved anode is thus provided which is not subjected to the disadvantages-of either metal or carbonaceous anodes.

What I claim is:

1. A gas filled rectifier tube comprising an anode formed partially of an electrically conductive metal and partially of a carbonaceous material and being free from concave surfaces which are exposed to ionic bombardment, and an outlet conductor, the carbonaceous portion of said anode being in electrical contact with said outlet conductor and the metal portion of said anode being in physical and electrical contact with said carbonaceous material but spaced from the outlet conductor.

2. An anode for gas filled rectifier tubes having opposite end portions and being free from concave cavities which are exposed to ionic bombardment, said anode being formed partially of a carbonaceous material and partially of an electrically conductive metal with the carbonaceous ly conductive metal which are in physical and electrical contact with each other and the metal portion being spaced from said opening, the metal portion of said anode constituting a portion of the outer surface of said anode and being free from concave portions which are subject to ionic bombardment.

4. A gas filled rectifier tube comprising a cathode, an anode spaced from said cathode, said anode having end portions and being formed partially of a carbonaceous material and partially of an electrically conductive metal, the metal portion of said anode forming at least a substantial portion of one end and being faced opposite to said cathode to receive ionic bombardment therefrom and being free from concave surface which are exposed to ionic bombardment, and the carbonaceous portion of said anode forming the opposite end of said anode, and an outlet conductor for supporting said anode, said conductor being spaced from the metal portion of said anode and being in physical and electrical contact with the carbonaceous portion of said anode. v

5. A gas filled rectifier tube comprising a cathode in the form of a filament, conductors extending through one end of said tube for support ing and heating said filament, an anode formed partially of a carbonaceous material and partially of an electrically conductive metal with the carbonaceous material constituting one end portion of the anode and the metal portion being arranged at the opposite end and being faced toward said filament to receive ionic bombardment therefrom, an outlet conductor extending through the opposite end of said tube and being embedded in the carbonaceous portion of said anode but spaced from said metal, said conductor being effective in supporting said anode and the metal portion of said anode being free from concave surfaces.

' FRED E. DIETZ. 

